Embodiments described herein relate generally to the preparation of battery cells and more particularly to systems and methods of preparing and using single pouch battery cells in a battery module.
Lithium-ion electrochemical (battery) cells typically include alternating layers of anode and cathode separated by separators. A combination of one anode and one cathode separated by one separator can be referred to as one stack. Multiple stacks are normally connected in parallel and inserted into a pouch to form a battery cell. The number of stacks within a battery cell (and according a pouch) is usually relatively large (e.g., >20) so as to increase the capacity. The pouch also includes an electrolyte (e.g., an organic solvent and dissolved lithium salt), normally introduced in a carefully controlled environment, to provide media for lithium ion transport. The amount of electrolyte within a pouch can be proportional to the number of stacks within the pouch, i.e., more electrolytes for more stacks.
In manufacturing, a battery cell can be constructed by stacking alternating layers of electrodes (typical for high-rate capability prismatic cells), or by winding long strips of electrodes into a “jelly roll” configuration (typical for cylindrical cells). Electrode stacks or rolls can be inserted into hard cases that are sealed with gaskets (most commercial cylindrical cells), laser-welded hard cases, or enclosed in foil pouches with heat-sealed seams (commonly referred to as lithium-ion polymer cells).
One promising application of lithium-ion battery cells is in automotive battery packs, which typically include a large number of battery cells, sometimes several hundreds, even thousands, to meet desired power and capacity needs. Each battery cell can further contain a plurality of stacks (i.e., anodes, cathodes, and separators) and electrode leads (i.e., tabs). Several cells are usually joined together through battery tabs and bus-bars (i.e., interconnecting units) to form a module. A typical battery pack can then include tens of such modules. As a result, a significant amount of jointing, such as welding, is normally needed to deliver the desired amount of power and capacity in a battery pack.